Hibiscus Problems: Fungus?

Hi all, I'm new here and so glad I've found this forum! I'm having problems with two of my hibiscus hybrids.

One is called Cosmic Dancer and is my favorite - but it's now developing brown spots on the leaves and the flowers are getting smaller. I live in Hawaii, up on the slopes so it's cooler than at sealevel. There's very little breeze, it's humid, and even with the cool temps, hibiscus do well up here (the common variety anyway.)

Here's a pix of the leaves (first 2 photos): (Is this a fungus? I see no bugs on this plant)

Also, I have another hybrid called Country Music, it's developing yellow spots on the leaves, some dark like the Cosmic Dancer, but overall looks quite different. Again, I see no bugs. Here's a pix: (last photo)

I just read someone's suggestion to try the apple cider vinegar spray, so I tried that this morning on one branch of each plant to see how it reacts.

Do you all agree this is fungus? Any other suggestions?

Thank you so much in advance for any advice! I love these plants like babies!

Ron's idea is a good one, doesn't sound too costly either. It is generally difficult to resolve pest/pathogen issues from photos online--there are just so many causes of brown, yellow and white spots. But you never know, someone very familiar with hibiscus may recognize the problem. Sorry I can not. Good luck with the plants though.

Thanks for the suggestion. It's not the cost - they are on a different island and I'm afraid the plant would be toast by the time I could mail them samples, if I'm even allowed to send through the mail. I am disabled so it makes it hard for me to take a sample into a local nursery.

If anyone does recognize this, please let me know. Someone told me they think it's a form of fungus "brown rot" - but I understand pictures aren't definitive. I just hate to lose this plant, it is absolutely the most beautiful flower I've ever seen. I do appreciate the suggestion - maybe I could try calling them.

I think a call to them or the local university (agricultural) extension office is a good idea. Often pathogen/pest issues are locally prevalent and thus more easily recognized by locals. And you never know, someone may have an idea here too.

Thanks again - I did get hold of UH Manoa and found out they have an outreach service here on Maui! So I'll try to get a sample to them asap. A bit difficult because of my disability, but I should be able to get a ride down there within the next week.

In the meantime, I may spray w/Neem as a precautionary - a diluted solution, I have used before with no ill effects.

I also examined the bottom of the pot and noticed the roots are extending quite a bit - maybe needs transplanting? - the roots are white and look healthy. I don't know how root bound they can be and remain happy.

Here's a photo of this flower and you can see why I'm so anxious to save it - thank you once more!

Attached Files:

This plant continues to lose leaves and the black spots continue to form. I have no transportation to the local UH Manoa campus and they demand one comes in to fill out a form and bring in samples.

I do have a fungicide which is also supposed to be "organic" and effective against common pests. I don't know whether to just try this and hope for the best. If I lose this plant, there's little opportunity to replace it as it's a hybrid which are difficult to find here, even if one does have transportation.

I know one shouldn't expose to sunlight after spraying, but for how long? I'm worried it's not getting enough sun as I've got it in a mostly shaded area at the moment. This is a potted plant, btw. I'm new at growing hibiscus and heartsick at the thought of losing such a previously healthy and beautiful plant-friend.

Any suggestions would be helpful (again, I'm disabled so that's why I can't drive in to the UH Manoa agricultural center).